Rotation mechanism



May 31, 1938.

J. c. cuRTls ROTATION MECHANISM Filed Aug. 12, 1936 2 I 33 34 I I //5/ INVENTOR BY ATTORNEY Patented May 31, 1938 UNITED STATES PATENT OFFICE ROTATION MEGHANISM Application August 12, 1936, Serial No.95,563

3 Claims.

This invention relates broadly to rock drills, but more particularly to a rotation mechanism for fluid actuated rock drills of the percussive type.

One object of this invention is to produce an improved rotation mechanism for rock drills, the mechanism having a reduced number of parts and affording a simple construction which is strong, durable and efiicient.

Other objects of this invention will be apparent from the following detailed description wherein similar character of references designate corresponding parts and wherein:

Fig. 1 is an elevational sectional view of the rock drill having the invention applied thereto.

Fig. 2 is a view similar to Fig. 1 illustrating some of the parts in different position.

Fig. 3 is a cross sectional view taken in a plane indicated by line 3-3 in Fig. 1.

Fig. 4 is a cross sectional view taken in a plane indicated by line 4-4 in Fig. 1.

Fig. 5 is a cross sectional view taken in a plane indicated by line 5-5 in Fig. 1.

Referring to the drawing, It! represents the cylinder of a rock drill having a hammer reciprocable therein for delivering blows to a tool implement (not shown). The upper end of the cylinder is formed with a relatively deep counterbore I2 accommodating a valve cap I3, valve housing I4 and a casing I5, which are locked therein against rotation by a dowel pin I 6. Within the valve casing l4, there is disposed a stationary valve bushing I1 having slidable thereon a valve IB automatically actuated for controlling the admission of the motive fluid into the cylinder for actuating the hammer Detachably secured above the cylinder ID in engagement with the casing I5, there is a back head I9 having a throttle valve rotatably mounted therein. This throttle valve is provided with a central bore 2| having motive fluid admitted therein in the usual manner.

The casing I5 is formed with a central bore extending therethrough, the bore being of differential diameters one of which, adjacent the valve housing I4, forms a cylindrical counterbore 22 having rotatable therein the head 23 of a rifle bar 24, which extends into the cylinder ID for interengagement with the hammer I. The head 23 has its upper end wall provided with ratchet teeth 25, the purpose of which will be explained hereinafter. Leading upwardly from the counterbore 22 there is a smaller counterbore accommodating the annular bead 26 of a small piston 21 slidably mounted within the bore extending through the casing. The upper end of this piston is reduced to form a stem 28 defining with the main body of the piston an annular shoulder 29. On the stem 28 is mounted a spring clip 30 engageable with the bottom of a small counterbore for limiting the downward movement of the piston. Provided within the casing I5, and disposed around the piston 21, there are four equally spaced fiat bottom holes 3| leading upwardly from the bottom of the cylindrical counterbore 22. Within each hole 3|, there is slidably mounted'a hollow plunger 32 constantly urged toward the disk 23 by a compression spring 33 mounted within the plunger and engaging the bottom of the hole 3|. The front end wall of this plunger is formed with teeth capable of operative engagement with the teeth 25 of the disk 23. The plungers 32 are located to extend inside of the marginal edge of the annular bead 26 of the piston 21, and to accommodate this bead each plunger is formed with a circular cut away portion constituting a step 34 with which the bead 26 is engageable for lifting the plungers away from the head 23. Through each plunger, there is a small port 35 leading from the interior of the plunger to a clearance provided between the head 26 and the adjacent wall of the plunger.

Centrally located through the back head I9, there is a bore 36 having a relatively small valve 31 rotatable therein and protruding from the back head to receive a handle 38, which carries a spring pressed plunger 39 engageable within notches formed on the head for locking the valve 31 .against accidental rotation.

Leading from the bottom of one hole 3| accommodating a plunger 32 to the valve 31, there is a port 40, which is capable of communication with the throttle valve chamber 2| through a passage 4| formed on the valve 31, and a port 42 leading from the valve 31 into the valve chamber 2|. The valve 31 is also in communication with the annular shoulder 29 formed on the piston 21 through a port 43, which port is capable of communication with the throttle valve chamber 2| through the port 42, a valve groove 44 and a valve passage 45. Through the valve 31, there is another port 46 opening to the atmosphere and capable of communication with the port 43.

From the throttle valve chamber 2|, motive fluid may be admitted to the automatic valve l8 through a plurality of ports 41, from where it is admitted into the cylinder I0 for actuating the hammer II in the usual manner. The cylinder I0 is also provided with a port 48 to allow the exhaust of the motive fluid from the cylinder.

In the operation of the mechanism, let us as- 55 sume that the valve 31 is positioned as shown in Fig. 1, and that motive fluid is admitted into the throttle valve chamber 2|. From this chamber, the motive fluid will flow through the ports 41 into the cylinder I I} for effecting the reciprocation of the hammer I I. Due to the engagement of the helical splines formed on the bar 24 with similar splines formed within the hammer II, it is obvious that the reciprocation of the latter will tend to cause the oscillatory motion of the bar. However, with the valve 31 positioned as shown in Fig. 1, motive fluid from the throttle valve chamber 2| is admitted on the annular shoulder 29 of the piston 2! via the port 42, valve groove 44, valve passage 45 and port 43, thus maintaining the piston 21 downwardly and allowing the engagement of the spring pressed plungers 3| with the disk 23. Since the end wall of each plunger is formed with teeth meshing with the teeth 25 of the disk 23, it will be understood that the rotation of the disk 23 and stem 24 in a B to A direction is prevented by the plungers 32, thus causing the hammer I I, during its upward stroke, to rotate in an A to B direction. During the downward stroke of the hammer II, the latter will tend to rotate the stem 24 in an A to B direction. In this instance the pawls 3| compressing the springs 33 will simply ride the teeth 26 of the disk 23, allowing the rotation of the latter without effecting the rotation of the hammer.

In a rock drill of the character described, the hammer I is operatively associated with the drill steel or tool implement by a suitable chuck connection, whereby the rotation of the piston in one direction is transmitted to the drill steel.

When it is desired to use the rock drill without imparting rotation to the drill steel, the valve 31 may be positioned as shown in Fig. 2. In this instance, motive fluid from the throttle valve chamber 2| will flow via the port 42, valve passage 4| and port 40 into the interior of one pawl 3|, from where it will be admitted on the front end of the piston 21 via the port 35. Simultaneously the motive fluid previously admitted on the annular shoulder 29 of the piston 21, is free to exhaust therefrom via the port 43 and valve port 48, allowing thereby the motive fluid acting on the front end of the piston 21 to drive the piston rearwardly. During this rearward motion of the piston 21, the annular bead 26 engaging the step 34 of the plungers 35, will move and maintain the plungers out of engagement with the teeth 25 of the disk 23, thus permitting the oscillatory motion of the stem 24 during the reciprocation of the hammer |I without effecting the rotation of the latter.

Although the foregoing description is necessarily of a detailed character, in order to completely set forth the invention, it is to be understood that the specific terminology is not intended to be restrictive or confining and it is to be further understood that various rearrangements of parts and modification of structural detail may be resorted to without departing from the scope or spirit of the invention as herein claimed.

I claim:

1. In a fluid actuated rock drill, the combination of a housing, a reciprocatory hammer in the housing, a rotatable rifiebar operatively associated with said hammer, teeth on said bar, a plurality of non-rotatable elements engageable with the teeth on said bar for locking the bar against rotation for effecting the rotation of said hammer, and a single fluid actuated member engageable with all of said elements for concurrently lifting and holding the same out of engagement with the teeth of said bar for allowing the bar to rotate instead of the hammer during the reciprocation of the latter.

2. In a fluid actuated rock drill, the combination of a housing, a reciprocatory hammer in the housing, a rotatable rifle bar operatively associated with said hammer, detents receiving means I on said bar, a plurality of non-rotatable detents disposed around the longitudinal axis of said bar movable into said detents receiving means on said bar for holding the bar stationary and effecting the rotation of said hammer, and means including a fluid actuated member coaxially disposed with said bar engageable with said detents for concurrently lifting and holding the same out of said detents receiving means for allowing the bar to rotate instead of the hammer during the reciprocation of the latter.

3. In a fluid actuated rock drill, the combination of a housing, a reciprocatory hammer in the housing, a rotatable rifle bar operatively associated with said hammer, a head on said bar having teeth formed thereon, a plurality of non-rotatable and axially movable elements engageable with said teeth for holding the bar stationary for effecting the rotation of said hammer, and a single fluid actuated piston engageable with all of said elements for axially lifting and holding the same out of engagement with said teeth for allowing the bar to rotate instead of the hammer.

JOHN C. CURTIS. 

